Al Gore's An Inconvenient Truth was a quietly persuasive documentary on global warming that probably made many converts. The Age of Stupid, starting with its in-your-face title, is what might be called "a hecture", a hectoring lecture on the same subject which, like a hell-fire sermon, might go beyond fire and brimstone and dismiss the very thought of hell altogether. The movie has a semi-fictional framework with a future archivist, played by Pete Postlethwaite, sitting in a giant concrete tower in the melted Arctic of 2055, telling us of the planetary neglect that led to his being the last surviving man. As Cyril Connolly put it: "Decay along with me, the worst is yet to be."

Postlethwaite is a powerful presence – the violent Scouse father in Terence Davies's Distant Voices, Still Lives, the earthly spokesman of the unspeakable Keyser Soze in The Usual Suspects, the Yorkshire socialist come south to scourge the lily-livered London liberals in Brassed Off.

Al Gore's soft sell is not his style – Bob Geldof's menacing: "Givus yer fuckin' money" is nearer the mark. The friendly witnesses he calls from his "archives" are a handful of good guys, most especially a Cornish-based,wind farm expert and his ecologically conscious wife and kids, and a weather-beaten Alpine guide who plants his own potatoes as he watches glaciers melt. The unfriendly ones, present under subpoena as it were, are oil companies despoiling Nigeria, middle-class nimbys, a likable young Indian tycoon, who wants to make air travel as possible for Mumbai rickshaw drivers as for jetsetters, documentary directors and celebrities scaling Kilimanjaro to help indigent Africans, and the rest of a reckless, thoughtless humanity.

I'm sure everything in Franny Armstrong's film is accurate, well researched and properly contextualised. But at the end I felt, for a while at least, that our civilisation is reaching its tipping point into oblivion, and that, like Kansas City as sung about in Oklahoma!, it's got about as far as it can go. I began to repeat to myself the refrain from William Empson's poem, "Just a Smack at Auden": "Waiting for the end, boys. Waiting for the end."